There is a technology for predicting, i.e. calculating, maximum inputtable power and maximum outputtable power as power parameters correlating with the output of a secondary battery, which is disclosed in, for example, Japanese Patent Publication No. 4788307. The technology disclosed in the Patent Publication predicts sustainable maximum inputtable power to second battery and sustainable maximum outputtable power from the secondary battery using an equivalent circuit model of the secondary battery. The equivalent circuit model, which consists of a single resistor and a single RC parallel circuit connected in series thereto, simulates the electrical consequences of the chemical reactions inside the secondary battery. The following describes the equivalent circuit model consisting of the single resistor and single RC parallel circuit as a single RC circuit model. The single resistor represents a charge-transfer resistance, and the single RC parallel circuit represents an RC parallel circuit comprised of a purely resistance and a double-layer capacitance connected in parallel thereto.
The following describes an example of how the known technology predicts sustainable maximum outputtable power for a secondary battery while the secondary battery is discharged.
First, the known technology collectively predicts unknown values of predetermined parameters representing the single RC circuit model of the secondary battery using an adaptive digital filter. Next, the known technology predicts, according to the predicted values of the parameters, a voltage across the positive and negative terminals of the secondary battery at the time when the secondary battery has been discharged for a predetermined time. Then, the known technology calculates a maximum output current when the voltage across the positive and negative terminals of the secondary battery becomes a predetermined minimum available voltage. Thereafter, the known technology calculates the product of the maximum output current and the minimum available voltage as the maximum outputtable power for the secondary battery.